Abstract
Nuclear proteins are targeted through the nuclear pore complex (NPC) in an energy-dependent reaction. The import reaction is mediated by nuclear localization sequences (NLS) in the substrate which are recognized by heterodimeric cytoplasmic receptors. hSRP1α is an NLS-binding subunit of the human NLS receptor complex and is complexed in vivo with a second subunit of 97 kDa (p97). We show here that a short aminoterminal domain in hSRP1α is necessary and sufficient for its interaction with p97. This domain is conserved in other SRP1-like proteins and its fusion to a cytoplasmic reporter protein is sufficient to promote complete nuclear import, circumventing the usual requirement for an NLS receptor interaction. The same aminoterminal domain inhibits import of NLS-containing proteins when added to an in vitro nuclear transport assay. While full-length hSRP1α is able to leave the nucleus, the amino-terminal domain alone is not sufficient to promote exit. We conclude that hSRP1α functions as an adaptor to tether NLS-containing substrates to the protein import machinery.
Original language | English |
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Pages (from-to) | 1818-1825 |
Number of pages | 8 |
Journal | EMBO Journal |
Volume | 15 |
Issue number | 8 |
Publication status | Published - 15 Apr 1996 |
Keywords
- hSRP1α
- NLS
- Nuclear import
- Nuclear localization signals
- Protein transport
ASJC Scopus subject areas
- General Neuroscience
- Molecular Biology
- General Biochemistry,Genetics and Molecular Biology
- General Immunology and Microbiology